"As fiscal uncertainty remains over the continuing resolution and possible sequestration, ICE has reviewed its detained population to ensure detention levels stay within ICE's current budget," the statement reads. "Over the last week, ICE has reviewed several hundred cases and placed these individuals on methods of supervision less costly than detention. All of these individuals remain in removal proceedings.

"Priority for detention remains on serious criminal offenders and other individuals who pose a significant threat to public safety."

U.S. Sen. Jeff Sessions, R-Mobile, blasted the moves in a news release this afternoon, saying the Obama Administration was using the sequester as an excuse "to bow to political pressure" from amnesty groups.

"The Administration's forced release of those in ICE custody further reduces the chances of reaching a bipartisan immigration accord," Sessions said. "There is no logical or rational reason why the 5.3 percent cut to ICE's operating budget would have to result in forcing law officers to immediately release already-apprehended illegal aliens and fugitives in federal detention.

"The last thing you would do to meet a budget cut of this size would be to voluntarily undertake actions that undermine the rule of law and endanger the public safety."

The blog Talking Points Memo reported ICE spokeswoman Barbara Gonzales said in an interview that the agency reviewed "several hundred cases" and put people in less-costly detention settings.

U.S. Department of Homeland Security Secretary Janet Napolitano told reporters at a White House briefing that the department won't be able to maintain its detention capacity in the face of the cuts, TPM reported.

The New York Times reported today that the cases against the released immigrants have not been dropped, rather they have been freed on supervised released.

The Times' also reported that immigration officials have not announced the number of released detainees, but immigrant activists have said "hundreds of detainees have been released from numerous ICE locations, including Alabama.

Christensen said ICE has not provided figures for the numbers of individuals released, including in Alabama.